Method 21. Open command prompt
2. Kill explorer using taskmanager
3. Run:
3. AT XX:YY /INTERACTIVE cmd.exe
3. where XX:YY is your Windows time plus one minute
4. Wait no more than one minute.
5. Now you have SYSTEM command prompt
6. Run explorer.
7. Ready to go!

- Quit the explorer with taskmanager.
- Run cmd.exe
- Type: AT HH:MM /INTERACTIVE cmd.exe (use your time + one minute for HH:MM)
Now you have a command line running with system users privileges
- Type explorer.exe

Firefox, WLM, Task Manager and underneath cmd are running on my user. The rest is running on SYSTEM.
I can even kill SYSTEM's explorer.exe using task manager from my admin account.

Problems:
When killing SYSTEM's explorer.exe, some parts of the environment (eg. Windows effects, desktop background) will still run on SYSTEM. To take the things back on normal, logoff then login with your previous account.
When starting explorer.exe, Windows will ask for Windows Tour, AND, will display an error saying that some network drives could not be reconnected, even if you don't have one.